[PATCH 1/3] elf: Allow dlopen of filter object to work [BZ #16272]

[Florian Weimer]

* David Kilroy:

>> Is there an expectation that libinternal interposes symbols in libA
>> etc., perhaps with more efficient implementations?  And if not, a
>> fallback implementation in libA etc. is used?  This is clearly not
>> supported by the Solaris filter feature (as documented).
>
> I'm not sure what you mean here. Libinternal.so is expected to supply the
> implementations for the symbols in libA.so. Ideally we wouldn't pick up
> other symbols from libinternal, but this is not an issue for us.
> If libinternal.so were to use IFUNC relocations for libA's symbols, I
> would hope it works, but I don't think that's being done.

I mean something like this.  libA defines f1, f2, f3.  libinternal
replaces f1 and f3 with optimized implementations, but not f2.
Applications which call f2 are expected to get the unoptimized
implementation in f2.

Thanks,
Florian